FAQ
Where do fine particles come from?
Every year in France, air pollution and fine particles cause 40,000 premature deaths. If we’re going to reduce that impact, we need to understand more about them. But behind the generic term “fine particles” lurks a variety of meanings. Fine particles can take different sizes and shapes, can be made up of different things, and can come from different sources. It’s time to take a closer look.
Natural and human-made sources
- Some fine particles come from natural sources and are difficult to prevent. They might be emitted during volcanic eruptions, desert sandstorms, forest fires or earthquakes. They can also be produced in sea spray and wind-eroded soil. Volatile organic compounds sometimes come from certain plant species and form fine particles in a chemical reaction with the air.
- But most fine particles are generated by humans. The top two sources are home heating in residential areas (wood-burning fires especially) and road transport. These activities are therefore respectively responsible for half and a quarter of fine particle emissions in Ile-de-France. Industry, construction,agriculture, forestry (spreading, tillage) and non-road transport also actively contribute to fine particle air pollution.
Primary particles, secondary particles and resuspended particles
Combustion, friction, chemical reactions: fine particles are generated for a variety of reasons.
- They can be emitted directly into the atmosphere due to combustion or friction, when a material is gradually broken down. These are known as “primary particles”. Primary particles are generated by forms of transport, home heating systems, and industrial or agricultural activities. In the case of petrol or diesel vehicles, fine particles come both from the exhaust gases produced by fuel combustion and from abrasion – friction – between brakes and tyres.
- But fine particles can also be created as a result of chemical reactions with atmospheric gases such as sulphur dioxide (SO2), nitrogen oxides (NOx) and volatile organic compounds (VOCs), known collectively as “secondary particles”.
- Once they have fallen to the ground, these fine particles have not yet finished their journey. They can be resuspended in the atmosphere. For example, fine particles on roads are lifted into the air again when a car passes.
Even though fine particles originate from various sources and phenomena, they are all dangerous to health and disruptive to ecosystems. Underestimated by lawmakers, this invisible threat nevertheless generates far too many medical issues and exposes local residents to dangerous and sometimes fatal diseases. A connection has been found with a number of respiratory (pharyngitis, tracheitis, bronchitis, asthma, etc.), cardiovascular (arrhythmia, heart attacks, thrombosis, etc.), and neurodegenerative diseases (Alzheimer’s, Parkinson’s) and an increased risk of cancer (particularly of the lungs). It is high time to eliminate out this evil.
Discover more questions
The term “fine particle” refers to an aggregate of polluting chemical compounds created during combustion, friction or chemical reactions. Forest fires, volcanic eruptions, and desert dust: fine particles can occur naturally. But most fine particles are generated by human activity. How? Mainly from road traffic (exhaust gases and abrasion caused by brakes on tyres and the road), home heating, and industrial and agricultural emissions.
Stinging eyes, breathlessness, a cough that won’t budge: air pollution – especially when it’s cause by fine particles – is irritating, but can also be the cause of serious diseases. It even puts lives in danger: in France, air pollution cuts life expectancy by two years. And in New Delhi, this figure leaps to 10 years. In terms of deaths on a global scale, air pollution is just as dangerous as smoking, and even more serious than alcohol and unclean water (there are three times as many air pollution-related deaths) and HIV (six times more). Who is most at risk? People suffering from respiratory and cardiac disorders, diabetes, infants, seniors and pregnant women.
Fine particles are harmful to human health. They can cause or exacerbate breathing and lung difficulties, cardiovascular diseases and even neurodegenerative diseases. This health risk can be limited if car owners would fit particle filters to their vehicles. Installed on exhaust or braking systems, particle filters are anti-pollution devices which capture fine particles emitted by vehicles. There are two types of particle filters: installations designed to capture particles from exhaust fumes generated by diesel and petrol vehicles, and those designed to recover fine particles from brake wear.